Implement setDoubleStep for QInputDialog

setDoubleStep works in the same manner as for setIntStep in that it is
just available for input dialogs getting a double.

[ChangeLog][QtWidgets][QInputDialog] Added setDoubleStep to enable
changing of the step amount for getDouble().

Task-number: QTBUG-17547
Change-Id: I5cabcfceb23324f8045f2b1e49017644418db01a
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/widgets/dialogs/qinputdialog.cpp

@@ -1367,6 +1367,41 @@ int QInputDialog::getInt(QWidget *parent, const QString &title, const QString &l
 double QInputDialog::getDouble(QWidget *parent, const QString &title, const QString &label,
                                double value, double min, double max, int decimals, bool *ok,
                                Qt::WindowFlags flags)
+{
+    return QInputDialog::getDouble(parent, title, label, value, min, max, decimals, ok, flags, 1.0);
+}
+
+/*!
+    \overload
+    Static convenience function to get a floating point number from the user.
+
+    \a title is the text which is displayed in the title bar of the dialog.
+    \a label is the text which is shown to the user (it should say what should
+    be entered).
+    \a value is the default floating point number that the line edit will be
+    set to.
+    \a min and \a max are the minimum and maximum values the user may choose.
+    \a decimals is the maximum number of decimal places the number may have.
+    \a step is the amount by which the values change as the user presses the
+    arrow buttons to increment or decrement the value.
+
+    If \a ok is nonnull, *\a ok will be set to true if the user pressed \uicontrol OK
+    and to false if the user pressed \uicontrol Cancel. The dialog's parent is
+    \a parent. The dialog will be modal and uses the widget \a flags.
+
+    This function returns the floating point number which has been entered by
+    the user.
+
+    Use this static function like this:
+
+    \snippet dialogs/standarddialogs/dialog.cpp 1
+
+    \sa getText(), getInt(), getItem(), getMultiLineText()
+*/
+
+double QInputDialog::getDouble(QWidget *parent, const QString &title, const QString &label,
+                               double value, double min, double max, int decimals, bool *ok,
+                               Qt::WindowFlags flags, double step)
 {
     QAutoPointer<QInputDialog> dialog(new QInputDialog(parent, flags));
     dialog->setWindowTitle(title);
@@ -1374,6 +1409,7 @@ double QInputDialog::getDouble(QWidget *parent, const QString &title, const QStr
     dialog->setDoubleDecimals(decimals);
     dialog->setDoubleRange(min, max);
     dialog->setDoubleValue(value);
+    dialog->setDoubleStep(step);
 
     const int ret = dialog->exec();
     if (ok)
@@ -1438,6 +1474,31 @@ QString QInputDialog::getItem(QWidget *parent, const QString &title, const QStri
     }
 }
 
+/*!
+    \property QInputDialog::doubleStep
+    \since 5.10
+    \brief the step by which the double value is increased and decreased
+
+    This property is only relevant when the input dialog is used in
+    DoubleInput mode.
+*/
+
+void QInputDialog::setDoubleStep(double step)
+{
+    Q_D(QInputDialog);
+    d->ensureDoubleSpinBox();
+    d->doubleSpinBox->setSingleStep(step);
+}
+
+double QInputDialog::doubleStep() const
+{
+    Q_D(const QInputDialog);
+    if (d->doubleSpinBox)
+        return d->doubleSpinBox->singleStep();
+    else
+        return 1.0;
+}
+
 /*!
     \fn void QInputDialog::doubleValueChanged(double value)
 

src/widgets/dialogs/qinputdialog.h

@@ -74,6 +74,7 @@ class Q_WIDGETS_EXPORT QInputDialog : public QDialog
     QDOC_PROPERTY(int doubleDecimals READ doubleDecimals WRITE setDoubleDecimals)
     QDOC_PROPERTY(QString okButtonText READ okButtonText WRITE setOkButtonText)
     QDOC_PROPERTY(QString cancelButtonText READ cancelButtonText WRITE setCancelButtonText)
+    QDOC_PROPERTY(double doubleStep READ doubleStep WRITE setDoubleStep)
 
 public:
     enum InputDialogOption {
@@ -178,6 +179,10 @@ public:
     static double getDouble(QWidget *parent, const QString &title, const QString &label, double value = 0,
                             double minValue = -2147483647, double maxValue = 2147483647,
                             int decimals = 1, bool *ok = Q_NULLPTR, Qt::WindowFlags flags = Qt::WindowFlags());
+    // ### Qt 6: merge overloads
+    static double getDouble(QWidget *parent, const QString &title, const QString &label, double value,
+                            double minValue, double maxValue, int decimals, bool *ok, Qt::WindowFlags flags,
+                            double step);
 
 #if QT_DEPRECATED_SINCE(5, 0)
     QT_DEPRECATED static inline int getInteger(QWidget *parent, const QString &title, const QString &label, int value = 0,
@@ -188,6 +193,9 @@ public:
     }
 #endif
 
+    void setDoubleStep(double step);
+    double doubleStep() const;
+
 Q_SIGNALS:
     // ### emit signals!
     void textValueChanged(const QString &text);

tests/auto/widgets/dialogs/qinputdialog/tst_qinputdialog.cpp

@@ -47,6 +47,7 @@ class tst_QInputDialog : public QObject
     static void testFuncGetDouble(QInputDialog *dialog);
     static void testFuncGetText(QInputDialog *dialog);
     static void testFuncGetItem(QInputDialog *dialog);
+    static void testFuncSingleStepDouble(QInputDialog *dialog);
     void timerEvent(QTimerEvent *event);
 private slots:
     void getInt_data();
@@ -61,6 +62,8 @@ private slots:
     void getItem();
     void task256299_getTextReturnNullStringOnRejected();
     void inputMethodHintsOfChildWidget();
+    void setDoubleStep_data();
+    void setDoubleStep();
 };
 
 QString stripFraction(const QString &s)
@@ -482,5 +485,45 @@ void tst_QInputDialog::inputMethodHintsOfChildWidget()
     QCOMPARE(editWidget->inputMethodHints(), Qt::ImhDigitsOnly);
 }
 
+void tst_QInputDialog::testFuncSingleStepDouble(QInputDialog *dialog)
+{
+    QDoubleSpinBox *sbox = dialog->findChild<QDoubleSpinBox *>();
+    QVERIFY(sbox);
+    QTest::keyClick(sbox, Qt::Key_Up);
+}
+
+void tst_QInputDialog::setDoubleStep_data()
+{
+    QTest::addColumn<double>("min");
+    QTest::addColumn<double>("max");
+    QTest::addColumn<int>("decimals");
+    QTest::addColumn<double>("doubleStep");
+    QTest::addColumn<double>("actualResult");
+    QTest::newRow("step 2.0") << 0.0 << 10.0 << 0 << 2.0 << 2.0;
+    QTest::newRow("step 2.5") << 0.5 << 10.5 << 1 << 2.5 << 3.0;
+    QTest::newRow("step 2.25") << 10.05 << 20.05 << 2 << 2.25 << 12.30;
+    QTest::newRow("step 2.25 fewer decimals") << 0.5 << 10.5 << 1 << 2.25 << 2.75;
+}
+
+void tst_QInputDialog::setDoubleStep()
+{
+    QFETCH(double, min);
+    QFETCH(double, max);
+    QFETCH(int, decimals);
+    QFETCH(double, doubleStep);
+    QFETCH(double, actualResult);
+    QWidget p;
+    parent = &p;
+    doneCode = QDialog::Accepted;
+    testFunc = &tst_QInputDialog::testFuncSingleStepDouble;
+    startTimer(0);
+    bool ok = false;
+    const double result = QInputDialog::getDouble(parent, QString(), QString(), min, min,
+                                                  max, decimals, &ok, QFlags<Qt::WindowType>(),
+                                                  doubleStep);
+    QVERIFY(ok);
+    QCOMPARE(result, actualResult);
+}
+
 QTEST_MAIN(tst_QInputDialog)
 #include "tst_qinputdialog.moc"